This is a variant of the special purpose weapon from M249 Light Machine Gun adopted by USSOCOM. The program, which led to both the Mk 46 and Mk 48, was headed by the US Naval Special Warfare Command (NAVSPECWAR). Like the SPW, the carrying handle, magazine insertion well, and vehicle mounting lugs have been removed to save weight. However, the Mk 46 retains the standard M249 plastic buttstock instead of the collapsible buttstock used on the SPW. The Picatinny rail forearm also differs slightly from the SPW. The Mk 46 has the option of using the lighter SPW barrel or a thicker, fluted barrel of the same length.Please Note: the above description is quoted from Wikipedia – the free encyclopedia on the web.

The MK 46 MOD 1 incorporates improved receiver pins, a feed tray with retention pawls and a vented handguard with improved heat shield and three MIL-STD 1913 rails. The MK 46 MOD 1’s cold hammer-forged MIL-SPEC barrel has a hard-chromed bore for longer life and improved accuracy, and serves as the mounting point for the carry handle. The receiver is formed steel and is equipped with a top-mounted MIL-STD 1913 optical rail. A hydraulic buffer greatly reduces recoil, helping the operator keep more rounds on target. The crossbolt safety and curved trigger help enhance operator control. Includes one spare barrel.Please Note: the above description is quoted from FNH USA.